Electronic timer



June 21, 1938. l R. E. coNovER 2,121,117

ELECTRONIC TIMER Filed March 1a, 1955 2 sheets-sheet 1 RICHARD E.CONOVER BY l June 21, 1938. R. E. coNovl-:R 2,121,117

ELECTRONIC TIMER Filed March 18, 1935 2 Sheets"-Sheet.2

INVENTOR RICHARD E CONOVER Patented June' 21, 1938 UNITED STATES PATENTOFFICE ELECTRONIC TIMER Richard E. Conover, Deer Park, Ohio ApplicationMarch 18, 1935, Serial No. 11,548

12 Claims.

My invention relates to electrical control circuits and moreparticularly to a control circuit having an ignition controlleddischarge tube which discharges at predetermined periods of time tocontrol a supply ci current to a load, such as a relay, or anotherdischarge tube, which, in turn, controls a load circuit.

In electrical control devices it is often desirable to control thesupply of current to loads,

I such as relays, indicating devices. color selectors, automaticcounters, safety gate operators, door openers, street lighting control,etc., in such a manner that current will be supplied to the load after apredetermined period of time, or it may i be desirable to supply currentto the load at intervals for a predetermined period of time. I

have provided an improved circuit which is' effective in initiating thesupply of current to a load after a predetermined time or which iseffective 3 in supplying current to a load at intervals for apredetermined period of time.

It is therefore an object of my invention to provide an improved iiashercircuit including an ignition controlled discharge tube which isdischarged at predetermined intervals of time, or the discharge of whichmay be varied so that current will flow through the circuit at variedintervals of time. Another object of my invention is to provide animproved circuit which operates at predetermined intervals of time tocontrol the supply of current to a load after a predetermined period oftime. A further object of my invention is to provide an improved circuitwhich is effective in controlling the supply of 3 current to loads atpredetermined intervals.

My invention will be better understood by reference to the accompanyingdrawings in which:

Fig. 1 is an improved flasher circuit showing means for passing currentthrough an ignition o discharge tube at predetermined intervals of time.

Fig. 2 is a series of curves showing the relationship between condenser,resistor and grid voltages and the time intervals at which a dischargepasses through the tube.

.3 Fig. 3 is a circuit for supplying current to loads after apredetermined interval of time.

Fig. 4 is a circuit for supplying and disconnecting the supply ofcurrent to loads at predetermined intervals of time.

Fig. 5 is a modification of the circuit illustrated in Fig. 4.

As illustrated in Fig. 1 of the drawings, my improved flasher circuitcomprises an ignition control discharge or grid glow tube I which is t5of the usual type and contains a vapor, such as V(ci. o-27) argon,helium, mercury, neon, or caesium. The discharge tube I is composed ofan anode plate 2, a cathode 3 and a grid 4. A resistor 5 is connected tothe conductor 6 leading from the plate to linut the current through thetube to a 5 safe value upon discharge. A condenser 'I is connected inparallel with the anode-cathode circuit of the tube between theconductor 8, leading from the plate and the conductor 9 leading to thecathode.

Current is supplied to the circuit from any suitable direct currentpower supply having a comparatively high voltage. As illustrated in thedrawings, the current passes through a resistor II which is connected tothe conductor 8. Part of the current from the line flows through dividedresistors I2 and I3 which are connected to conductors 8 and 9 inparallel with the condenser and the remainder is utilized in chargingthe condenser. Two resistors are provided so that the voltage acrosscondenser 1v may be divided at a xed ratio.

A source of grid potential, such as a battery I4, is connected incircuit with the potentiometer I5 by means of conductors I6 and to apoint I1 between the divided resistors I2 and I3. The grid is connectedto the battery circuit at a predetermined point on the potentiometer I5so that the desired amount of voltage may be supplied to the grid.

In accordance with my invention, the grid oi the tube is arbitrarilymade negative with respect to the cathode by means of the battery I4 andpotentiometer I5. In this connection it will be particularly noted thatthe difference in potential between the grid and the cathode may bevaried by means of the potentiometer I5.

The operation of my improved iiasher circuit will now be apparent.Starting with the condenser 1 discharged, current from the line ilowsthrough resistor II to the conductor 8 and into the condenser 1. Sincethe sum o! the resistors I2 and I3 is very large in comparison toresistor I I, the condenser cannot discharge itself through resistors I2and I3 as fast as it receives a. charge from the line through theresistor II. The net result is that the voltage on the condenser buildsup as indicated by curve I8, Fig. 2. Since resistors I2 and I3constitute a voltage divider for the condenser voltage the potentialacross Il rises along with the voltage across condenser 1. As thepotential across resistor I3 rises, however, the net negative grid biasis slowly 'extinguished `until the voltage across the resistor I3 equalsthe predetermined negative voltage between the grid 5l and the cathode.At this point, discharge occurs and the voltage across the resistor I3and the condenser 1 drops to zero. The cycle is then repeated.

The time between cycles may be made constant or may be varied by varyingthe setting of the potentiometer I5. This is illustrated in Fig. 2 oi'the drawings in which the ordinal designates the voltage and theabscissa the time. As illustrated, the voltage across condenser 1 risesrapidly as indicated by the curve I8 and then gradually assumes aconstant value. The voltage across resistor I3 rises in proportion withthe condenser voltage as indicated by the curve I9 while the gridvoltage, designated by the line 20, is constant. When the voltage acrossthe resistor I3 becomes sufiicient to neutralize 'the original negativeb ias between the grid and the cathode, discharge occurs and thecondenser voltage drops to.zero. As illustrated in Fig. 2 this occurs atthe time designated T1. The cycle is then repeated and if the negativepotential of the grid with respect to the cathode is maintained at thesame value, the discharge during the second cycle will occir in the sameperiod of time as indicated by T, on the drawings. If the diierence inpotential between the grid and the cathode is set at a lower value, asindicated by the line 2I, and the grid potential is made less negativewith respect to the cathode 3 than in the previous example, thedischarge will occur sooner as indicated at Ta. On the other hand, whenthe negative grid bias is increased, as indicated by the lines 22 and23, the time o! discharge will be increased as indicated at T. and T. ofthe drawings.

My improved flasher circuit may be employed for various purposes, suchas controlling relays, or may be utilized to control another ignitiondischarge tube. For example, in Fig. 3 of the drawings, a circuit isshown in which the flasher circuit controls the operation of anotherignition control discharge or grid glow tube for supplying current to a.load. The flasher circuit is similar to that disclosed in Fig. 1 and theparts have accordingly beeny designated by the same reference numerals.As illustrated, the second tube 44 is composed of an anode 25 connectedto the conductor I0 and a cathode 26 connected to the conductor 3. Thegrid 21 is normally maintained negative with respect to the cathode 26by means of a source o! potential, such as a battery 28, and isconnected to the conductor 29 leading from the cathode 3. A resistor3611s connected in series with the conductor 29 between the point ofconnection of conductor 30a leadlng from battery 28 and the conductor 9.

The operation oi' the circuit for supplying current to the load 3i willnow be apparent. When a discharge occurs in ignition tube I, the voltageacross resistor 30 is momentarily increased. This voltage, however, isof a different polarity and greater than the voltage of battery 28. Thegrid potential with respect to the cathode is thus made positive whichcauses a discharge in tube 24 causing current to now to the load 3|. Asthe plate is supplied by direct current voltage, current will continueto ow to the load after the grid potential has dropped back to anegative value. The load current can only be interrupted by opening theswitch 33. It will thus be apparent that by my improved flasher circultcurrent may be supplied to the load after a predetermined interval oftime and will continue to flow until the switch 33 is turned oit.

The resistor 32 is connected in series with the battery to preventexcessive grid current after the discharge of the tube.

Figs. 4 and 5 of the drawings illustrate a cir-` cuit for supplyingcurrent to a load and disconnecting the supply of current at desiredintervals. As shown in the drawings, the flasher circuit is designatedby the same numerals as in Fig. 3. In this circuit the ignition controltube 34 is composed of an anode 35, a cathode 36 and a grid 31. Theanode 35 is connected to a source of alternating current 38 and the gridis normally maintained negative with respect to its cathode by a sourceci' potential, such as a battery 39, and potentiometer 45. In thearrangement of this circuit a conductor 4I leading from the positiveside of the battery is connected to the conductor 29 leadingfrom thecathode 3 and a condenser 42 is connected in series with conductor 29which leads toconductor 9. A variable resistor 43 is connected to theconductor 4I in parallel with the condenser 42.

The use of a flasherl circuit for supplying and disconnecting the supplyof current to the load 3i will now be apparent. When tube I discharges,the condenser 42 charges and the potential across the condenser, beingof opposite polarity to the battery 39, raises the potential oi grid 31with respect to cathode 36 to a positive value and the tube 34discharges, thereby supplying current to the load 3|. Condenser 42 thenyimmediately commences to discharge through the resistor 43 which is of acomparatively high value. The charge in the condenser, however, issufllcient to maintain the voltage of grid 31 positive with respect tocathode 36 for the desired length of time. When the condenser dischargesto such a point, however, that the potential across the resistor is lessthan the potential of battery 39 and potentiometer 45, the grid voltagebecomes zero and then negative. Since the plate. voltage in this case,however, is supplied by alternating current, when the grid becomesnegative it regains control and the current to the load is disconnected.

The length of time which current is supplied to the load may be variedeither by changing the value of the resistor 43 or by changing thenegative grid voltage by means of the potentiometer 45. I find itadvantageous to make both of these values variable. For instance, theresistor 43 may be a tapped resistor and the inal adjustment may be madein potentiometer 45. It will be understood that the adjustment of boththe load and flasher circuits is correlated so that the load is turnedoiI before the next discharge occurs through tube I.

Fig. 5 of the drawings discloses a modification of the circuit in Fig.4. In this case a potential divider is placed across the high voltagesupply line consisting of resistors 46, 41, 43 and 49. Resistor 41 ismade variable so that the difference in potential across resistor 49 maybe made constant irrespective oi' the setting of resistor 46.

The operation of this circuit is the same as that disclosed in Fig. 4with the exception that instead of utilizing a. separate source ofvoltage to make the grid voltage negative with respect to its cathode,the conductors leading from the cathodes are returned to a point whichis more positive than the conductors leading from the grids. Forinstance, the lead from cathode 3 is returned to the resistor 46 andthelead from cathode 36 is returned to resistor 43. Since the n cathode ofeach tube is thus made more positive than the respective grids, thepotential of the grid with respect to the cathode will be negative undernormal conditions. As the potential across resistor I3 rises, however,the negative grid bias will be overcome and a discharge will occur intube l. The discharge of tube I will change the potential of grid 31with respect to the cathode 36 in the same manner as described inconnection with Fig. 4 and the load will be turnedon. After thecondenser 42 discharges the grid will become negative and the current tothe load will be turned oil?. It is apparent that the same method ofobtaining the various potentials from a common source is applicable 'inthe circuits illustrated in Figs. 1 and 3 of the drawings.

From the foregoing description it will be seen that I have provided animproved flasher circuit by means of which a discharge through the tubemay be eiected at predetermined intervals of time, which may be variedin accordance with the desired requirements.

It will also be apparent that I have provided an improved circuit bymeans of which current may be supplied to a load after a predeterminedinterval of time after the flasher circuit has been set in operation.

It will also be seen that my improved flasher circuit is effective forsupplying and disconnecting current to a load at predetermined intervalsof time which may be varied according to the desired requirements.

It will be understood that while I have designated the loaddiagrammatically in the drawings, the circuit may be employed forcontrolling any desired apparatus, such as relays, automatic scales,color selectors, automatic counters, safety gate operators, positionindicators, door openers, street lighting controls, smoke detectors,etc.

To those skilled in the art many modications and widely differentembodiments and applications of my invention will suggest themselves`without departing from the spirit and scope thereof. My disclosure anddescription are purely illustrative and are not in any sense limiting.

What I claim is:

1. An electrical control circuit comprising an ignition controlleddischarge tube having an anode, a cathode and a grid, said tube being ofa type in which Aan electric discharge may be started in response to apredetermined electrical condition of the grid and in which theymagnitude of the discharge is independent of the electrical conditionof the grid, a condenser connected vin parallel with theanode-cathodecircuit of said tube, a resistor divided into two portionsconnected in parallel with said condenser, means for normallymaintaining the grid of said tube at a negative potential with respectto its cathode, means for charging said condenser and creating 'adifferencev of potential across one of said resistors which is less thanthe di'erence of potential across said condenser, and means responsiveto the change of` potential across the portion of the resistor having alower potential than thev condenser for changing the potential of thegrid with respect to its cathode to lsuch a value that the dischargeoccurs in the tube, thereby causing a discharge of the condenser throughthe tube and immediately restoring the Anegative potential of the gridwith respect to its cathode.

2. An electrical control circuit comprising an ignition controlleddischarge tube having an anode, a cathode and a grid, said tube being ofa type in which an electric discharge may be started in response to apredetermined electrical condition of the grid and in which themagnitude of the discharge is independent of the electrical condition ofthe grid, a condenser connected .in parallel with the anode-cathodecircuit of said tube, a resistor divided into two portions connected inparallel with said condenser, variable means for normally maintainingthe grid of said tube at a negative potential with respect to itscathode, means for charging said condenser and creating a difference ofpotential across one of said resistors which is less than the differenceof potential across said condenser, and means responsive to the changeof potential across the portion of the resistor having a lower potentialthan the condenser for changing the potential of the grid with respectto its cathode to such a value that the discharge occurs in the tube,thereby causing a discharge of the condenser through the tube andimmediately restoring the negative potential of the grid with respect toits cathode.

3. An electrical control circuit for supplying current to a loadcomprising a circuit including a discharge tube having an anode, acathode and a grid, said tube being of a type in which an electricdischarge may be started in response to a predetermined electricalcondition vof the grid and in which the magnitude of the discharge isindependent of the, electrical condition of the grid, a second dischargetube having an anode,

a cathode and a grid, means for normally maintaining the grid of the rsttube negative with respect to its cathode, a condenser in parallel withthe anode-cathode circuit of the rst tube and a resistor connected inparallel with said condenser, means for charging said condenser from adirect current source of power and creating a difference in potentialbetween the anode and cathode of Ithe second tube and across saidresistor from the same source of power, means responsive to the rise inpotential across said resistor for changing the grid potential of therst tube with respect to its cathode suiliciently to cause a discharge,and means responsive to the discharge of the first tube for causing animmediate discharge in the second tube, whereby direct current will becontinuously supplied to the load through the second tube.

4. A time relay for delaying the supply of current to a load for apredetermined period of time after application o! supply voltage,comprising a circuit including a discharge tube having an anode, acathode and a grid, said tube being oi.' a type in which an electricdischarge may be started in response to a predetermined electricalcondition of the grid and in which` the magnitude of the discharge isindependent of the electrical condition of the grid, means for normallymaintaining the grid oi' the tube negative with respect to its cathode,a .condenser in parallel with the anode-cathode circuit oi' the tube andhaving a resistor connected in parallel therewith, means for chargingsaid condenser and creating a difference in potential between the anodeand cathode of saidtube from a direct current source of power, meansresponsive to the rise of potential across said condenser and parallelresistor for changing the grid potential of the tube in the positivedirection sumciently to cause discharge responsive to the discharge oi.'the tlrst tube for causing immediate discharge of the second tube,whereby current will be continuously supplied to the load through thesecond tube.

5. A time relay i'or delaying the supply of current to a load for apredetermined period of time after application of the supply voltage,comprising a circuit including a discharge tube having an anode, acathode and a grid, said tube being of a type in which an electricdischarge may be started in response to a predetermined electricalcondition of the gridand in which the magnitude of the discharge isindependent of the electrical condition o1' the grid, means for normallymaintaining the grid of the tube negative with respect to its cathode, acondenser in parallel with the anode-cathode circuit of the tube havinga resistor connected in parallel therewith, means for charging saidcondenser and creating a difference in potential between the anodel andcathode of said tube from a direct current source of power, meansresponsive to the rise of potential across said condenser and parallelresistor for changing the grid potential of the tube in the positivedirection sufficiently to cause discharge of the tube. a seconddischarge tube which functions as a line switch tosupply current to aload from the source of power common to the first tube, and meansresponsive to the discharge of the tlrst tube for causing immediatedischarge of the second tube, whereby current will be continuouslysupplied to the load through the second tube.

6. In combination, a flasher circuit including a discharge tube havingan anode, a cathode and a grid, and means for normally maintaining thegrid of said tube negative with respect to its cathode, a seconddischarge tube having an anode, a cathode and a grid, a load in serieswith the second discharge tube, means associated with the cathode of thenrst tube and the grid of the second tube for normally maintaining thegrid of the second tube negative with respect to its cathode, a sourceof direct current voltage connected to the anode of both tubes, meansresponsive to the supply of direct current voltage to the tubes forcausing a discharge of the first tube in a predetermined time aftercurrent is supplied thereto, and means responsive to the discharge ofthe first tube for temporarily changing the grid bias of the secondtube, whereby current from adirect current source oi' power is suppliedto the load through the second discharge tube.

7. In combination, a flasher circuit including a discharge tube havingan anode, a cathode and a grid, a direct current source of powerconnected to said circuit, and means responsive to the supply ot currentfor causing repeated discharges of said tube at predetermined intervalsafter current is supplied thereto, a second discharge tube having ananode, a cathode and a grid, a load in series with the second dischargetube, means for supplying current from an alterhating` current source ofpower to the second tube, means associated with the cathode o! the firsttube for normally maintaining the grid of the second tube negative withrespect to its cathode, and means responsive to the discharge of thefirst tube for changing the grid potential of the second tube in apositive `direction sumciently to permit discharge for a predeterminedportion of the time between the discharges of the first tube, thuspermitting current to be supplied to a load for predetermined intervalsbetween the discharges of the first tube.

8. In combination, a flasher circuit including a discharge tube havingan anode, a cathode and a grid, and a condenser in parallel withtheanode-cathode circuit of the tube, a second discharge tubecontrollable by the first tube having an anode, a cathode and a grid, aload in series with the second tube, means for normally maintaining thegrids of both tubes negative to the respective cathodes, a resistorcommon to the discharge circuit of the first tube and the gridcathodecircuit of the second tube, means for supplying voltage from a singledirect current source of power to charge the condenser in series withthe first tube and to create a difference of potential between the anodeand cathode oi' the second tube, means responsive to the charge of saidcondenser for changing the grid bias of the first tube in a positivedirection sufficiently to cause discharge of the first tube, meansresponsive to the discharge of the first tube for creating a differenceof potential across said resistor, and means responsive to the rise ofpotential across said resistor for instantly changing' the grid bias ofthe second tube in a positive direction sufllciently to cause dischargeof the second tube, whereby a direct current flows continuously from thesingle source of supply to the load through the second tube.

9. In combination, a flasher circuit including a discharge tube havingan anode, a cathode and a grid, a condenser in parallel with theanodecathode circuit of said discharge tube, a resistor in parallel withsaid condenser, and means for normally maintaining the grid of said tubenegative with respect to its cathode, a second discharge tubecontrollable by the first discharge tube, a load in series with thesecond discharge tube, a source of potential connected to the cathode ofthe first tube and the grid of the second `tube for normally maintainingthe grid of the second dischargevtube negative with respect to itscathode, a second resistor common to the discharge circuit of the firsttube and the gridcathode circuit of the second tube, means for applyingvoltage from a direct current source of power to the condenser inparallel with the first tube and to the anode of the second tube, theresistor in parallel with said condenser being associated with the gridof the first tube in such a manner that an increase in potential acrosssaid resistor changes the grid bias of the first tube in a positivedirection sufliciently to cause discharge of the first tube in apredetermined period of time', thereby creating a temporary dierence oi'potential across the second resistor, and means responsive to the risein potential across the second resistor for instantly changing the gridbias of the second tube in a positive direction sufliciently to causedischarge of the second tube, whereby current flows to a load throughthe second tube.

l0. In combination, a flasher circuit including an ignition controlleddischarge tube having an anode, a cathode and a grid, a. condenser inparallel with the anode-cathode circuit of said tube, means for normallymaintaining the grid of said tube negative with respect to said cathode,a direct current source of power connected to the circuit for chargingsaid condenser, means responsive to the discharge of said condenser forchanging the grid bias of said tube in a positive direction sumcientlyto cause discharge of `said tube, means responsive to the discharge ofsaid tube for charging a second condenser connected to the cathode ofsaid tube. and means for permitting discharge ofthe second condenser,

- a second ignition controlled discharge tube having an anode, a cathodeand a grid, means for supplying current from an alternating currentsource ,of power to the anode of the second tube, means for normallymaintaining the grid of the second tube negative .with respect to itscathode, and a connection between the cathode of the iirst tube and thegrid of the second tube whereby the charging of the second condenser fchanges the grid bias of the second tube in a suiiiciently positivedirection for a predetermined period or" time to permit discharge of thesecond tube.

11. In combination, a flasher circuit ,including an ignition controlleddischarge tube, 'a source of direct current connected to said circuit,means associated with the circuit and responsive to the supply oicurrent for lautcrnatically causing re peated discharges of said tube atpredetermined intervals after current is supplied thereto, and acondenser in series with the cathode of said tube which is chargedduring the discharge of said tube, a resistor in parallel with saidcon-v denser through which the condenser is discharged, a seconddischarge tube having an anode, a grid and a cathode, a. load in serieswith the second discharge tube, means for vsupplying current from analternating source of power to the second tube, means for normallymaintaining the grid of the second tube negative with respect to itscathode, and means whereby the discharge of the condenser in the ashercircuit maintains the grid of the second tube in 'repeated discharges ofsaid tube at predetermined intervals after current is supplied thereto,a second discharge tube having an anode, a cathode and a grid, means forsupplyingcurrent from an alternating current source of power to thesecond tube, means for normally maintaining the grid of the seconddischarge tube negative with respect to its cathode, a condenser inseries with the rst tube having a resistor in 'parallel therewith, saidcondenser and resistor being associated with the grid of the second tubein such a manner that upon discharge of the first vtube the grid bias ofthe second tube is changed in a positive direction to a suicient valueto allow current to ow through the second tube for a predeterminedperiod o time, the capacitance of said condenser and the resistance ofsaid resistor being of such a value that the grid bias of the secondtube will be restored to its normal negative value before recurrenceoi?A the discharge of the first tube.

RICHARD E. CONOVER..

